As mobile phones began to be used, message communication started to become popular, and as mobile phones evolved to smartphones, the message calls got bigger in number than the voice calls. Furthermore, the smartphone is not used simply for a message delivery, but for the input of non-vocabulary terms such as a web address and e-mail due to its function as a multimedia communication means. This non-vocabulary input is inconvenient due to the cases for which it is inevitable to input characters and symbols alternately, unlike the case of general input of characters. Nevertheless, when the full keyboard of a computer is used, the input of characters and symbols is easily done, but it is much more difficult than inputting characters only on mobile devices which need to input with only two fingers. Especially it is very difficult to input characters and symbols using the keypad consisting of 12 keys including the numbers 0 to 9 and ‘*’ and ‘#’ keys. In order to input just the alphabetic characters, the disambiguation input method using 12 keypads has been used in the English-speaking countries. However, the input of the phrases mixed with the alphabets and symbols as in the cases mentioned above is inconvenient since characters and symbols are inputted separately. In this background, the present invention provides a method enabling the input of not only words but also phrases or sentences including symbols and ‘spaces’ for a keypad composed of a conventional twelve keys by utilizing the disambiguation input method which has been widely used in the English-speaking countries.